This invention relates to a horizontal power band saw, such as may be used for cutting metal stock (e.g. bar stock, pipe, or structural shapes) to a desired length.
Generally, a horizontal powered band saw includes a bed supported on legs and a head pivotally mounted with respect to the bed for swinging between a raised, retracted position and a lowered sawing position. The head has a pair of spaced blade wheels journalled thereon with an endless band saw blade entrained around the blade wheels. A vise is typically provided on the bed for holding the work to be cut. The band saw blade typically has a cutting edge along one side thereof and the head includes blade guides engagable with one reach of the blade (the lower reach toward the bed when the head is lowered) for twisting the blade so that the cutting edge of the blade between the blade guides is disposed toward the work and for twisting the blade in reverse direction so that the blade may be engaged by the blade wheels. Conventionally, the blade drive wheel is driven by a variable speed drive and motor and the other blade wheel, the idler wheel, is journalled on an axel slidable on the head toward and away from the drive wheel for tensioning the blade.
Desirably, the endless band saw blade should be tensioned so as to remain taut as it cuts through the work. This tension load should be sufficiently high so as to insure straight cuts through the work, but not so high as to break the blade. The tension load on the blade will vary from blade-to-blade, depending on the width, thickness, type of blade, and the material from which the blade is fabricated. By insuring that a proper tension preload is placed on the blade, the service life of the blade can be enhanced. Further, it is neccessary for the idler wheel to be adjustable so as to compensate between blades of various length. Heretofore, it has been difficult to insure that a desired preload is applied to the blade.
Prior horizontal power band saws typically utilize rigid castings to form all or part of the bed and the frame for the head. While these prior band saws constructed of these castings were highly rigid, they were costly to manufacture.
As mentioned above, horizontal band saws conventionally included a pair of spaced blade guides for twisting the lower reach of the band saw blade so as to orient its cutting edge toward the work and to accurately hold the blade as it cuts through the work. Prior blade guides oftentimes included guide rollers, or friction carbide inserts for twisting and holding the blade and thrust bearings for transferring the cutting thrust from the blade to the head. However, with prior horizontal band saws it was sometimes difficult to adjust the rollers, thrust bearings and inserts so as to properly engage the blade, or upon changing from one blade to another of different thicknesses or widths.
Further, the work holding vises of prior art horizontal power band saws typically included a fixed jaw and a movable jaw manually movable toward and away from the fixed jaw on the bed of the saw. The jaw could be moved between an open and closed position by rotating the vise screw. However, in utilizing the band saws to repeatedly cut off lengths of structural members or bar stock material, the manual manipulation of the vise was a relatively time consuming operation and thus contributed to relatively long cycle times to cut consecutive lengths.
Among the several objects and features of the present invention may be noted the provision of a horizontal power metal cutting band saw, such as described above, having a frame fabricated from rolled structural elements welded together to form weldments (as opposed to castings) with the frame having sufficient rigidity and strength for accurate cuts and long service life;
the provision of band saw which is of economical construction and which requires less tooling costs for manufacture than prior art band saws;
the provision of such a band saw which is relatively easy to manufacture and service;
the provision of such a band saw in which a predetermined tension load may be readily and accurately applied to band saw blades of varying lengths and types thereby to enhance cuts made by the blades and to enhance the blade life;
the provision of such a band saw in which the saw controls, including the feed rate and feed pressure of the saw, are readily accessible by an operator;
the provision of such a band saw utilizing formed structural elements for its frame in which the head of the saw is accurately and rigidly pivotally secured to the bed of the saw and yet in which the pivotal connection of the head to the bed is adjustable so as to enable accurate alignment of the head to the bed and so that the head is positively held in its aligned position in respect to the bed;
the provision of such a band saw having a quick-acting work-holding vise which may be readily and conveniently manually operated by the saw operator so as to effect the rapid release and gripping of a work piece upon repeated cuts being made on the work piece;
the provision of such a band saw in which the speed of the saw blade may be readily varied;
the provision of such a band saw having blade guides which may be readily and accurately adjusted so as to properly support and guide blades of varying thicknesses;
the provision of such a band saw which accurately supports the blade while sawing; and
the provision of such a band saw which can accommodate stock of relatively large size.
Other objects and features of this invention will be in part apparent and in part pointed out hereinafter.